County Londonderry (Contae Dhoire or Doire in Irish) is one of the six counties of Northern Ireland, in the province of Ulster. It was named for its main town (later city and administrative centre), Derry (later Londonderry), and the Plantation of Ulster by London livery companies.
As with the town, its name is subject to the Derry/Londonderry name dispute, with the form Derry preferred by nationalists and Londonderry preferred by unionists. The name Derry is almost always used in the Republic, while the British authorities use the name Londonderry.
Unlike the town, historically there was not a preceding County Derry: it was established by combining the former County of Coleraine with small parts of Counties Antrim, Donegal, and Tyrone at the behest of the London companies so that they could control both banks of the mouths of the River Foyle and the River Bann and have access to sufficient wood for construction. The county town was Coleraine.
